Circular blade sawmills using multiple circular saw blades are known, sometimes referred to as “edgers” or “edger mills”. Edgers are generally used to take the bark off the edges of fresh-sawn boards, or to straighten crooked boards. “Gang” edgers usually have a pair of spaced circular blades driven on a common shaft with a fixed spacing. “Shifting” edgers also have pairs of spaced blades, but at least one of the blades in the pair can be moved left and right to adjust the blade spacing and thus the width of the board. A chain and gripping mechanism is often used to pull the lumber through the blades.
A good example of a prior art shifting edger is the Corley Junior Edger, manufactured as early as the 1940's by the Corley Manufacturing Company of Chattanooga, Tenn. The Corley Junior Edger had a stationary blade and a movable blade driven on a common shaft.
Two-bladed edger mills are usually mounted on long steel roller frames, and are useful for processing lumber on a commercial scale. Edger mills are not as useful for home hobbyists or small commercial carpenters, who generally use smaller single-bladed table saws.